Situated in the extreme Southwest of the Algarve region of Portugal, the city of Lagos has its roots in the ancient Roman settlement of Lacóbriga. It also probable that prior to the Romans the Phoenicians had a settlement on or close to the present town.

During the 7th Century AD, the southern part of the Iberian Peninsula including the Algarve, was conquered by Islamic tribes emanating from North Africa and the Middle East. These people were know as "the Moors" or "Arabs", but, in fact, their origins were as diverse as Syria, Persia and Judea, a fact visible even to day in the names of many Algarve villages and towns. Those who settled in Lagos contributed to the development of the nascent city walls and defences.

Following the renaissance of the Christian Kingdom of Portugal in the 12th Century AD, the Portuguese royal family made various efforts to re-conquer the Algarve, which was effectively, accomplished by the end of first half of the 12th Century AD.
Lagos increased in importance when shortly after the conquest; the regional military government was transferred from Silves to Lagos.

However, this was not to be its only claim to fame. The city, together with the village of Sagres, 30 kms. distant, during the next three centuries, was to become key not only to the future development of Portugal but also to the whole Western Europe.

It was from here, that the famous scion of the Portuguese Royal Family, Infante Dom Henrique or Prince Henry the Navigator, sponsored missions of exploration along the West Coast of Africa. This resulted in the opening of the sea route from Europe to India and the subsequent development of the empires of not only Portugal, but also the Netherlands, United Kingdom, France, Spain and Belgium.

Many seamen on the voyages of exploration originated from Lagos, which resultantly turned into a commercial and naval port of consequence. It was from Lagos that the caravels, developed by Portuguese shipwrights, sailed to encounter new worlds in Africa and America and subsequently brought back gold, ivory and slaves, all of which greatly contributed to the wealth of both the city and nation. The Slave Market building still standing today in central Lagos was built to accommodate this trade.

Several famous ships masters on the original voyages licensed by Prince Henry, hailed from Lagos Navigators. Several such as Gil Eanes, Álvaro Esteves and Lançarote Freitas are, to this day, commemorated in the names of some of the principal streets of Lagos.

When the Prince died in 1460, his body was first buried in the old Church of Santa Maria. Subsequently, it was transferred to the Chapel of the Monastery of Batalha, situated 100 kms. North of Lisbon.

In 1578, the then king, D. Sebastião, raised Lagos to the status of a city, and from its harbour left on a fatal expedition against the Moors in North Africa from which he never returned.

Construction of the outer town walls was started in 1520 during the reign of King Manuel to afford increased protection from piracy and raiders. The security Lagos thus afforded both, in military, and in naval terms owing to its excellent harbour situated close to the Atlantic and the routes to India and America, resulted in it becoming a major port during the XVIth and XVIIth centuries. Several important naval engagements were fought in Lagos bay, including an infamous occasion when the ships of Sir Francis Drake were reported to have fired on vessels in the bay.

Lagos remained the capital of Algarve until 1756, when owing to the fact that a large part of its infrastructure and architectural legacy was destroyed by the earthquake of 1755, the capital was transferred away from the city to Faro.

Today, the town is primarily a destination for holidaymakers. However, it still retains the atmosphere of its great cosmopolitan heritage, a fact readily visible to the visitor in its wealth of architecture and monuments.